I had the 4wt built for me by a custom rod maker out in Wyoming. I told him what I wanted and sent some pictures of what I liked. He did a great job and I am very pleased with it. He hand shaped the cork grip.
The 3wt (lower rod in the top picture) is one I did. I bought the handle kit from janns net craft cat # 250734 http://www.jannsnetcraft.com/fly-rod-handle-kits/ and installed it myself.
I use the 4wt for tailwater trout and the 3wt for mtn fishing and bream in the warmwaters. nothing like a bluegill on a full flexing rod!
The handles are called cigar grips